possible head gasket failure?

[javalin]

Hiya

If I list the symptoms - can somebody check my logic? Also is there a common location where the head gasket fails on the mk3 GTI's? Engine in question is the 8v AGG - about 80k miles.

1) Oil residue in the air box - despite cleaning
2) Oil being blown out of the oil filler cap
3) "Blowing" noise from the airbox when there is any load on the engine. Exhaust has been checked twice and is 100% ok.
4) Gurgling / running fluids sound when the oil cap is removed when the engine is running. By this I don't mean the puff-puff-puff sounds of the compression cycle. Sounds like air is blowing through fluid (oil!?).
5) Possibly a very slight water loss - but this could be a minor radiator leak - so not so worried about this one
6) Lumpy idle
7) Its very hard to drive smoothly when hot and in traffic - i.e. start stop - low RPM. Never sure whether it'll shoot off or stall when I pull off.
7a) Cylinder compression was 165,165,145,145 (PSI)
9) No mayonase. No oil in the water. No overheating.

Have checked the PCV breathers - all clear. My hypothosis is that the gasket is starting to give between 3 & 4 and into the oil channels? Is this a common failure?

Local garage is not convinced - mainly I think due to (9).  Other forum suggested engine wear - but this a new thing - recent problem.

Cheers much!
James

[Wayne]

Oil being blown out of the oil filler cap is a sign of crankcase pressure, if I am correct then your looking at rings or bore wear.

[tomsdubs]

Does not sound like head gasket, bottom end if you ask me especially with those compression readings.

[tomsdubs]

Also does it smoke out the exhaust, colour? smell? Use your nose 

[Guy]

Also does it smoke out the exhaust, colour? smell? Use your nose 

that's a useful tip right there kids... to smell something, use your nose! 

[javalin]

>Also does it smoke out the exhaust, colour? smell? Use your nose
what am I smelling for?  No smoke other than white out of the exhaust in the mornings that I remember - not driven it for a while, whilst waiting for garage to get round to looking at it.

>if I am correct then your looking at rings or bore wear.
aka expensive?  You mean rings as in Piston rings? If so can they be changed with the engine in the car?

Thanks all for your help so far,

James

[Wayne]

>Also does it smoke out the exhaust, colour? smell? Use your nose
what am I smelling for?  No smoke other than white out of the exhaust in the mornings that I remember - not driven it for a while, whilst waiting for garage to get round to looking at it.

>if I am correct then your looking at rings or bore wear.
aka expensive?  You mean rings as in Piston rings? If so can they be changed with the engine in the car?

Thanks all for your help so far,

James

Not really, it could be done but quicker to remove and rebuild out of the car.

[javalin]

ok - Thanks Wayne.

>bottom end if you ask me especially with those compression readings.
what should be expecting?  I think, from memory, auto-data and bentley seem to be about 10bar - so 160psi or so?

Cheers,

James

[Wayne]

ok - Thanks Wayne.

>bottom end if you ask me especially with those compression readings.
what should be expecting?  I think, from memory, auto-data and bentley seem to be about 10bar - so 160psi or so?

Cheers,

James

Yes but you have 2 at 145 which is low ish.

[javalin]

ok - so thinking piston rings on cyl 3 & 4?  Is that a common problem on these?  I ask as i've a mk3 1.8 GL as well - that has similar compression readings, lumpy idle etc, but no oil blowing.

edit -> Just spoke to local garage who have been looking at it.  They recon their machine gets 180psi within 10% across 4 cylinders.  Hmmm.  Something is not right, if there is good compression where is the "blowing" noise and oil comming from?

Thanks again,

James